Three DNA-Dependent ATPase Activities from Cultured Mouse FM3A Cell

Three peaks of DNA-dependent ATPase activity were found in an extract of cultured mouse FM3A cells by fractionation with phosphocel-lulose column chromatography. These ATPase activities were decreased or missing when the enzymes were extracted from non-growing cells arrested at saturation density, evidence that these activities are related to the regulation of cell growth. Our characterization of these enzyme activities showed differ-ences in their dependencies on single-stranded DNA, optimal pH, the Mg++ requirement and sensitivity to 2-mercaptoethanol.